Ether dissolves the alkaloid.—If nitric acid gives first a scarlet, then a yellow color, sulphuric acid a yellow, changing to red and violet, and hydrochloric acid a violet color, the alkaloid present is probably veratrine.
If the above colorations are not produced, chlorine water is added to another portion of the substance, then ammonia; the formation of a green color, changing to violet and turning red upon a renewed addition of chlorine water, denotes the presence of quinine.
In case all of these tests give but negative results, and the alkaloid is soluble in concentrated sulphuric acid, a solution being formed which assumes a reddish-violet tint when stirred with a glass rod previously dipped in bromine water, the presence of delphine.
is indicated.
Ether fails to dissolve the alkaloid.—If the substance is capable of being sublimed,[N] it consists of cinchonine.
b. Ammonia produces a precipitate, which redissolves in an excess of the precipitant, but separates out after the lapse of an hour.
The substance is treated with cold absolute alcohol and its solubility in this menstruum noted. If it readily dissolves, it probably consists of brucine.
The presence of this alkaloid is confirmed by applying the following tests: (1) Nitric acid imparts a blood-red color to the substance; (2) if treated with sulphuric acid, it acquires a reddish tint which subsequently changes to yellow and green; (3) chlorine at first fails to cause a coloration, but after some time a yellow color which afterwards changes to a red is produced; (4) upon treating the substance with bromine, it immediately assumes a violet tinge.
In case the alkaloid is only slightly soluble in alcohol, there is reason to infer the presence of strychnine.
The following confirmatory tests should be applied: (1) If the substance is treated with a mixture of sulphuric acid and an oxidizing body, such as bichromate of potassa, binoxide of manganese, or peroxide of lead it acquires a violet color, which changes into red and finally passes into a clear yellow; (2) the addition of bichloride of platinum produces a precipitation of the hydrochlorate.
Should, however, the substance be only slightly soluble in alcohol, and the above reactions fail to take place, the presence of solanine.
is indicated. In presence of this alkaloid the following reactions will occur: (1) Upon treating the substance with concentrated sulphuric acid, it assumes a rose tint, which changes after some time has elapsed first to a deep violet, then to a brown color; (2) a solution of a salt of the alkaloid reduces gold and silver salts; (3) the addition of oxalic acid produces a precipitate in the aqueous and even acid solution of its salts.